Machine for shaping spur gears



June 24, 1941. G. FISCHER MACHINE FOR SHAPING SPUR GEARS 4 Sheets-Sheet1 Filed Aug. 24, 1938 Java/liar I Fzsc he 7' 0. By W, M

June 24, 1941. I G. FISCHER 2,246,671

MACHINE FOR SHAPING SPUR GEARS Filed Aug. 24, 1938 4 Sheets-Sheet 2 Fig.2'

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MACHINE FOR SHAPING SPUR GEARS Filed Aug. 24, 1938 '4 Sheets-Sheet 3.772 van; far:

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G. FISCHER MACHINE FOR SHAPING SPUR GEARS Fil'ed Aug. 24, 1938 4Sheets-Sheet 4 .712 21'6 n for: 6. E'scke Patented June 24', 1941 UNITEDSTATS T GFFECE Georg Fischer, Zollikon, Switzerland, assignor toMaag-Zahnriider und-Maschinen A. G., Zurich,

Switzerland Application August 24, 1938, Serial No. 226,415 In GermanyAugust 28, 1937 (C1. Shh-9) 4 Claims.

My invention relates to a machine for shaping spur gears by means of atool of the rack-type operating in accordance with the rolling process.More particularly, my invention relates to a machin of this kind inwhich the tool of the racktype is at least as long as the circumferenceof the spur gear to be out and, therefore, may cut a Whole gear within asingle cycle of operation without any intervening indexing motions.

An object of my, invention is to provide a machine of this kind which isreliable and accurate in operation and may be readily set up for work ofdifferent pitch circle diameter. Further objects of my invention willappear from a description of a preferred embodiment thereof followinghereinafter.

In the drawings,

Fig. 1 is a side view of the machine, partly in section,

Fig. 2 is an exploded view of the driving and controlling mechanism ofthe machine showing a plan view of some of the elements illustrated inFig. 1,

Fig. 3 is a representation similar to that of Fig. 2 of a modifieddriving mechanism,

Fig. 4 is a section taken along line 4-4 of Fig. 1 showing different setups for spur gears of different diameters to the left and to the rightof the dash-dotted line, and

Fig. 5 shows some of the mechanism of Fig. 2 on an enlarged scale.

The bed I is provided with an upright having a swivel member rotatableabout a horizontal axis provided with a guide extending within avertical plane. On this guide there is slidingly mounted a ram 2carrying the tool 5| of the rack-shaped type. The ram is reciprocated bymeans of a connection rod 3 and a crank t of the shaft 5. The shaft 5 isdriven through gears "l, B, 9, It which are attached to the crank shaft'5 and two parallel gearshafts 6, II respectively. Moreover, on theshaft If there is fastened a bevel gear l2 engaging another bevel gearit which is driven by an electric motor l5 through a belt It.

A second drive serving to produce the rolling motion is derived from theshaft 6. For this purpose, a gear I6 is secured to this shaft andoperates a gear [9 through a reduction gearing l1, l8 loosely mounted onthe shaft H. The gear I9 drives a gear 23 through the intermediary of ashaft and gears 2| and 22. The gear 23 is attached to one end of a shaft24, the other end of which carries a reversing gear. The reversing gearcomprises two bevel gears 25 and El provided with clutch teeth 25 andfreely rotatably mounted on the shaft 24. These bevel gears, which aresuitably secured against axial displacement on the shaft 24, are in meshwith a common bevel gear 29. Between them, there is splined on shaft 24a shiftable clutch sleeve 30 provided with a peripheral groove.Depending on whether the clutch sleeve is shifted to engagement with oneor the other of the two bevel gears 26 and 27, the bevel gear 29 isrotated in one direction or the other. The bevel gear 29 drives meshingspur gears 3! and 32. The gear 32 is attached to a shaft or spindle 33journalled in a bearing slidably mounted, as at 33 in a support 52 topermit said support to have adjustment in a direction transversely ofsaid shaft and. the shaft suitably secured against axial displacementtherein. Within this support, the shaft 33 is formed as a screw spindle34 engaging a nut 35 which is attached to a slide 36. This slide 36 ismovable on longitudinal guides ll, Figure 1, which are provided on thesupport 42 and extend horizontally at right angles to the crank shaft 5.

Therefore, when the shaft 33 is rotated in the one direction or theother, the slide 36 moves longitudinally on the support 42. The support42 in its turn is slidably mounted on guides 13 which are provided onthe bed I below the ram 2 and extend parallel to the crank shaft 5. Ascrew spindle 53 provided with a hand wheel 14 is journalled within adepending lug of the support 42 and secured against axial displacementtherein. This screw spindle 53 engages a nut 15 attached to the bed I.Therefore, rotation of the hand wheel M causes the support 42 to behorizontally adjusted on the bed I in a direction parallel to the crankshaft 5.

The slide 38 is provided With a vertical bearing it having acomparatively large diameter for a purpose to be explained hereinafter.In this bearing, there is journalled a circular bearing member 3'!constituting a rotary work table or work spindle. This member has aconical bore accommodating a mandrel 38 attached therein. The downwardlyprojecting cylindrical end of this mandrel is journalled in a dependingportion til of the slide 3t. On th mandrel there is attached a masterspur gear i0 engaging a rack it. This rack and the rack M are locatedWithin a common plane indicated by the dotted line 11 which extendsparallel to the axis of the work spindle 3i and is preferably verticallydisposed. This is the plane in which the tool 5| performs itsreciprocatory cutting motion relative to the work spindle 31.

It is an important feature of my invention that the machine may be soset up as to cut gears of different diameters. For this purpose, themaster gear it may be readily exchanged. When the operator wishes totake off the master gear ll] and to replace it by another one, he needonly lift the spindle 3? out of its bearing it. Then, th master gear maybe readily taken off the mandrel 38.

In order to avoid interference of the master gear with the removal ofthe work spindle, the diameter of the bearing member 3! is made largerthan the largest gear that is to be cut on the machine.

In order that the rack ll will properly engage th master gear ieirrespective of the diameter thereof, the rack ll is transverselyadjustable towards and away from the work spindle. The means forperforming this adjustment comprise a wedge 43 more clearly shown inFig. 4 which is inserted between the rack 45 and a vertical shoulder l8provided on the support 42 and extending at an acute angle to the plane11. The wedge =13 may be longitudinally adjusted by means of a set screwit. After adjustment the rack may be fixed by a screw 15 pressing therack against a fixed stop it and by threaded bolts ll extending throughslots of the wedge into threaded bores of the rack ii. By tightening thebolts 41 the wedge is firmly clamped between the rack s! and theshoulder 18.

The master gear lil must be so dimensioned that its pitch circle equalsthat of the gear to be cut. The number of its teeth, however, may bechosen as desired. For this reason, the same rack ll may be usedtogether with various master gears 2-8 for cutting gears of differentsizes and numbers of teeth. It is only necessary to adjust the rack iito the proper distance from the axis of the spindle 3'! to eliminatelost motion between the rack and the master gear 46. Preferably, aplurality of wedges of different width are kept in store. Fig. 4 showsthat a wedge 53 of small width is required in combination with a largemaster gear it, while a wide wedge 43 is required in connection with asmall master gear til.

On the table 3? there is attached a chuck it including a mandrel 38 onwhich the blank 50 is attached. The rack-shaped tool 5| is preferablymounted on a swivel plate 52 which, in its turn, is mounted on a clapperplate (not shown) hinged about a horizontal pivot to the ram.

The pitch circle of the master gear is accurately coaxial with the pitchcircle of the work gear rolling along the pitch line of the tool 5i.Therefore, the two gears ll! and 56 perform the same rolling motion. Byadjustment of the hand wheel 14 and by the consequent transversedisplacement of the support 42, the work piece fill and the tool 5| maybe relatively adjusted to the proper radial distance without affectingthe relative adjustment of the rack 41 and the master gear 40.

The mechanism for the manual and automatic control of the reversing gear26, 2'! is illustrated in Figs. 2 and .3. The peripheral groove of theclutch sleeve 39 is engaged by a fork 28 pivotally mounted on a bracketwhich is suitably attached to the support Q2. The fork 28 forms one armof a bell crank lever, the other arm of which is connected to a rod 83which islongitudinallyshiftably mounted on the support 32 and extendsparallel to the guide H and carries two adjustable stops M. These stopsproject into the path of a member 61 projecting from the longitudinalslide 36 and may be so adjusted as to be engaged by the member 67 whenthe slide 36 has completed its rolling motion. Owing to such engagement,the sleeve 3% is moved to its neutral position in which it engagesneither of the gears 26 and 21 thus stopping the slide 38.

For starting the rolling motion of the slide the operator must shift acontrolling lever 54 shown in Figs. 2 and 5 from its middle position 0to one or the other of its end positions a and b.

This controlling lever 5 3 is mounted on the support 32 and is connectedwith a pinion 66 engaging rack teeth 65 provided on the rod 63.Therefore, the reversing gear is moved to one or the other of itsoperative positions when the controlling lever 54 is moved to itsa-position or its b-position. Moreover, the controlling lever 5 isconnected with a toothed sector engaging a pinion attached to arotatable disc 55 provided with two opposite peripheral recesses 56. Inthe operative positions of the controlling lever 54 one or the other ofthese recesses 56 is in registry with one arm of a two-armed lever 57cooperating with a press button 58 of a control switch 59 whereby thepress button is released so as to automatically close a starter switch62 controlling the motor it. The shaft H operated by the motor it drivesthe ram 2 as well as the reversing gear 25-28. 5

The operator first inserts a master gear it having the same pitch circlediameter as the gears to be out. Then, he must insert a proper wedge 63and accurately adjust the same by means of the screw ii whereupon thescrew 45 and the bolts 47 are tightened. Having thus completed thesettings determining the proper rolling motion, the operator puts ablank on the chuck 49 and adjusts the support 52 by the hand wheel 14 toproperly position the work blank so that the pitch line of the rack 51will be tangent to the pitch circle of the gear to be cut.

After these adjustments have been performed, the operator moves the handlever 54 from its neutral c-position to either the a-positon or theb-position depending on whether the slide is in its left end position orin its right end position. This causes the ram 2 to reciprocate and theslide 36 to start its motion, whereby the work blank 53 is caused toroll along the rack 5| the length of which is at least equal to thecircumference of the pitch circle of the master gear and, therefore,equal to the length of the rack 4|.

When the motion of the slide 36 has started, the tool begins with itsone end to cut out the teeth of the work piece. It will be recalledthat, when the control lever 54 is shifted in one direct1on or theother, the reversing gear is at the same time shifted into one of itsoperative positions through the elements $6, $5, 63, 28 and 39, wherebythe shaft 24 driven by the motor I5 is cooperatively connected with oneof the two bevel gears 26, 2'5 which drives the shaft 33 and thus causesthe slide 36 to move along the guides ll of the support 42 in adirection parallel to the rack it. Since the master gear 46 engages therack 45 without any lost motion, it rolls along this rack with itsentire periphery. The work piece 523 performs exactly the same motion asthe master gear 40.

The engagement of the projection 61 with one or the other of the stops64 occurs, when the master gear has completed one revolution and thencauses the reversing gear to be shifted to its neutral position. At thesame time, the rack teeth 55 shift the sector 66 and the controllinglever 54 to the c-position thus turning the disc 55 through a quarter ofa revolution. This causes the lever 51 to be so turned as to press onthe button 58 of the control switch 59 which, in its turn, causes theautomatic starter 52 to stop the motor l5. Therefore, the entire machinestops. The work piece is now finished and may be removed and replacedwith a new blank. Then, the control lever is shifted to b, whereuponanother cycle of operation is initiated in which the rolling motion isperformed in the opposite direction.

It may be desirable under certain conditions to operate on the sameblank in two successive cycles, in the first cycle roughening the gearteeth with a comparatively high rolling speed and in the second cyclefinishing the gear teeth with a slower rolling motion in the oppositedirection.

For performing such an operation, I may modify the reversing gear asshown in Fig. 3. In this modification, the two bevel gears 26 and 2'!mesh with two different coaxially arranged bevel gears 29, 29. The gear29 is connected for common rotation with the spur gear 3|. Similarly,the bevel gear 29' is connected with a spur gear 3|. These two spurgears have different numbers of teeth. They are in permanent engagementwith two gears 32 and 32 rigidly attached to the shaft 33. Owing to thisarrangement, the shaft or spindle 33 will operate the slide 36 at ahigher speed when driven by engagement of the clutch sleeve 3|) with thebevel gear 21, but will operate the slide at a lower speed, when thesleeve engages the bevel gear 26. As the speed of reciprocation of theram 2 is independent of the speed of the rolling motion of the blank 50which is directly proportional to the number of revolutions of the shaft33, the number of teeth of the gears 3|, 32 may be so selected as toobtain any desired number of cutting strokes per tooth.

As stated, the same rack 4| may be used for producing gears of differentdiameters and different numbers of teeth but that the master gear 4|]must be so chosen as to have the same pitch circle diameter as the gearto be cut. The adjustment of the rack 4| to proper engagement with themaster gear is performed by means of a wedge 43 of a properly selectedwidth. Obviously, however, the same wedge may be used in connection withmaster gears of different diameters provided that a bar of suitablewidth is interposed between the wedge and the shoulder 18.

My improved machine is equally well adapted to the manufacture of gearshaving straight teeth or gears having helical teeth. For cutting ahelical gear it is only necessary to turn the swivel member 10 about itsaxis, whereby the guide of the ram 2 is positioned obliquely inaccordance with the angle of the gear teeth.

The swivel plate 52, however, is preferably so adjusted as to hold therack 5| parallel to the rack 4|, provided of course, that the tool rack5| has oblique teeth corresponding to the helix angle of the gear to becut.

I have not deemed it necessary to illustrate the exact location of thebearings of the various. gears and their shafts. However, the gears 9,I0, 2|, 22 and 23 are preferably so located as to be readily accessibleand interchangeable. By exchanging these gears and selecting gears ofproper numbers of teeth, the cutting speed and the rolling speed may bevaried, as desired. Also, the gears 3|, 3| and 32, 32 may beinterchangeable so as to enable the operator to modify the ratio of therolling speeds of the slide 36 in both of its directions, if desired.

The reversing gear and its associated elements are preferably mounted onthe support 42 while the gears transmitting motion from the motor IE tothe ram and tothe shaft 24 are mounted in the upright of the bed I. Topermit of a transverse adjustment of the support 42 on its guide 13, theshaft 24 is preferably splined in the gear 23 so as not to interferewith such transverse adjustment.

My invention is capable of numerous modifications which will readilyoccur to anyone skilled in the art. Thus, it is primarily the relativemotion between the different elements that is of importance and the samerelative motion may be obtained in a number of various ways by keepingone or the other element stationary, as desired, while permitting theother elements to move. Therefore, the invention is not limited to theexact details of the described embodiment 1 but is to be broadlyinterpreted in accordance with the claims following hereinafter.

What I claim is:

1. In a machine for shaping spur gears, a reciprocatory ram, a tool ofthe rack-type mounted on and extending transversely of the ram, asupport, a rack mounted on said support in a common plane with said tooland coextensive therewith, a slide slida'bly mounted on the support tohave movement parallelly of said rack, a work spindle journalled in saidslide to rotate in a plane parallel to said tool and rack, a spur gearrotatable with said work spindle meshing with said rack, said toolhaving a length not less than the circumference of said spur gear, meansfor imparting reciprocatory movement to the ram and cutting motion tosaid tool in a plane parallelly of the axis of said work spindle, andmeans for mounting and adjusting said fixed rack towards and away fromsaid work spindle, comprising a wedge engaged between the edge of therack opposite the rack teeth and a wall portion of the support, a screwspindle connected to the wedge for longitudinally shifting said wedge,and means releasa-bly securing the wedge in adjusted position.

2. In a machine for shaping spur gears, a tool of the rack-type, a racklocated in a common plane with said tool and coextensive therewith, aslide adapted to move parallel to said rack, a work spindle journalledin said slide and extending parallel to said plane, a spur gear attachedto said work spindle and meshing with said rack, said too-l having alength not less than the circumference of said spur gear, means forproducing a relative reciprocatory cutting motion between said tool andsaid work spindle within said plane, means for moving said slideincluding a screw spindle, driving means for said screw spindle, areversing gear operatively connected to the driving means. adapted toconnect said screw spindle to the driving means to rotate the screwspindle in one or the other direction and thereby move the slide in oneor the other direction, a linkage manually operative for shifting saidreversing gear from its normal neutral position to connect the screwspindle and slide to the driving means to be actuated in one or theother direction, and means operative at a predetermined movement of saidslide to actuate said linkage to shift said reversing gear from itsoperative position into its neutral position and automaticallydisconnect the screw spindle and slide from the driving means and stopthe operation thereof.

3. In a machine for shaping spur gears, the combination comprising atool of the rack-type, a rack located in a common plane with said tooland coextensive therewith, a slide adapted to move parallel to saidrack, a work spindle journalled in said slide and extending parallel tosaid plane, a spur gear attached to said work spindle and meshing withsaid rack, said tool having a length not less than the circumference ofsaid spur gear, means for producing a relative reciprocatory cuttingmotion between said tool and said work spindle within said plane, andmeans for moving the slide in either direction including a motor, amotor switch, a screw spindle driven by said motor and driving saidslide, a reversing gear interposed between said motor and said screwspindle, a linkage adapted to shift said reversing gear from its neutralposition to one or the other of its operative positions and a connectionbetween said linkage and said motor switch, whereby the motor is startedwhen the reversing gear is moved from its neutral position and isstopped when the reversing gear is moved into its neutral position.

4. In a machine for shaping spur gears, a tool of the rack-type, a racklocated in a common plane with said tool and coextensive therewith, aslide adapted to move parallel to said rack, a bearing in said slide, abearing member journalled in said bearing having an annular flange atone end to engage and support the bearing member from the bearing toextend in a plane transversely of the rack, a Wonk carrying mandrelmounted in said bearing member, a spur gear attached to said workcarrying mandrel and meshing with said rack to rotate the bearing memberwith the work mandrel by the movement of the slide longitudinally of therack, said tool having a length not less than the circumference of saidspur gear, the opening in the bearing and the lbearing member being of adiameter larger than the spur gear and permit removal of the bearingmember with the spur gear as a unit from the bearing, means forproducing a relative reciprocatory cutting motion between said tool andsaid Work spindle within said plane, means for adjusting said fixed racktowards and away from said work spindle, comprising a wedge disposed atthe edge of the rack opposite the rack teeth and a fixed wall of theslide, and a screw spindle connected to and operative for longitudinally shifting said wedge.

GEORG FISCHER.

